I’m not sure what the fact that TIN has been used previously has anything to do with anything. Yes, it has been used before, usually in a development context without explanation of what they were even talking about unfortunately.
Either way, there’s no excuse for using the term TIN Cities in a marketing document, when they have always been called photogrammetry. Cardinal rule of marketing… NEVER use acronyms, unless it’s a household word like NASA or FAA.